1. Field of the Invention
The present invention generally relates to a divider, and more particularly to a low power consumption frequency divider circuit using the configuration of current reused circuit to form the common current path.
2. Description of the Related Art
In communication system, the local oscillator is used to provide a mixing signal for up-converting a low frequency modulated signal or down-converting a radio frequency (RF) signal to be modulated. Thus, most power consumption appears in the local oscillator. To avoid un-effective power consumption, low power and full integrated frequency divider is required.
The frequency divider is widely used in the wire or wireless communication. There are several types of RF frequency divider, comprising (1) type of common mode logic, CML; (2) type of static logic; (3) type of dynamic logic; (4) type of miller divider and (5) type of injection locking frequency divider. Each one has its advantages and disadvantages. For examples, types of the common mode logic and miller divider can operate at very high frequency but have disadvantage of high power consumption. Type of dynamic logic has advantage of very low power consumption but operate at low frequency. By considering the power consumption and working frequency, type of the injection locking frequency divider is a preferred choice.
Currently, the injection locking frequency divider uses inductor-capacitor (LC) tank resonator to be the basic oscillator, to realize the injection locking frequency divider. The injection locking frequency divider using the LC tank resonator can be further divided into (1) direct injection locking frequency divider and (2) harmonic injection locking frequency divider. Direct injection locking frequency divider provides an oscillating signal to a LC tank resonant oscillator through a switch. The structure of the oscillator is a conventional differential LC tank inter-coupled oscillator. However, the differential LC tank inter-coupled oscillator use two current paths, thus causing much power consumption of the circuit. Prior art can be found in U.S. Pat. No. 4,806,872 issued to Cowley al., entitled “Frequency modulation receiver employing frequency divider”. It discloses the frequency modulation receiver using injection locking frequency divide. The disclosed oscillator uses many current paths, thus causing much power consumption of the circuit.
To overcome the aforementioned problems, there is needed to provide a novel frequency divider. Thus, in the present invention, a novel low-power consumption frequency divider circuit using the configuration of current reused circuit to form the common current path for reducing the power loss is disclosed.